Autonomously and semi-autonomously controlled machines are capable of operating with little or no human input by relying on information received from various machine systems. For example, based on machine movement input, terrain input, and/or machine operational input, a machine can be controlled to remotely and/or automatically complete a programmed task. By receiving appropriate feedback from each of the different machine systems during performance of the task, continuous adjustments to machine operation can be made that help to ensure precision and safety in completion of the task. In order to do so, however, the information provided by the different machine systems should be accurate and reliable. The pose of the machine includes parameters whose accuracy may be important for control and positioning of the machine. For example, the pose of the machine may include position, velocity, orientation, acceleration, etc. of the machine.
Conventionally, machines may include a positioning system that relies on Global Navigation Satellite System (GNSS) data along with data from an Inertial Measurement Unit (IMU), which typically includes one or more accelerometers, to calculate the pose of the machine. The IMU may consist of, for example, a 3-axis accelerometer, 3-axis angular rate gyros, and sometimes a t-axis inclinometer. These sensors may need to be properly aligned with each other in order to provide an accurate pose solution. If these sensors are not aligned correctly, the pose calculation may be inaccurate as this inaccuracy may ultimately affect the performance of the machine. The causes of sensor misalignment are many and may include improper calibration, lack of calibration, or some physical movement of the sensors on the machine due to replacement, damage, or other unrelated maintenance.
U.S. Patent Publication No. 2013/0211716 to Kellar (“the '716 publication”) discloses an arrangement in which a gross direction error is determined by calculating a difference between the vehicle direction indicated by the GNSS device and the direction indicated by the IMU device. Based on the direction error, the '716 publication determines whether the vehicle is traveling in a forward or reverse direction.
Although the arrangement of the '716 publication may provide a way to determine a direction error, it may not determine an alignment error. For example, it may not determine an alignment error where one of the two devices (e.g., GNSS device and IMU) is pitched, yawed, or rolled with respect to the other device. When an alignment error is present due to one device being pitched, yawed, or rolled with respect to the other device, the pitch, heading, and roll calculation of the machine may not be accurate.
The positioning system of the present disclosure is directed toward solving one or more of the problems set forth above and/or other problems of the prior art.